In addition, you can add your own bindings system-wide to /Library/KeyBindings/DefaultKeyBinding.dict, or per-user to ~/Library/KeyBindings/DefaultKeyBinding.dict.

This page has a nice overview of bindings. I've grown particularly fond of Transpose (⌃-T), which swaps the two letters to the left and right of your cursor, fixing my most common kind of typo quickly.

In addition, there are various additional tricks using the ⌥ and ⌘ keys:

⌘-← and → move to the beginning or end of the line. Add ⇧ to select everything in between.

⌘-↑ and ↓ move to the beginning or end of the document. Add ⇧ to select everything in between.

⌥-← and → move to the beginning or end of the word, or between multiple words. Add ⇧ to select everything in between.

⌥-↑ and ↓ move to the beginning or end of the paragraph. Add ⇧ to select everything in between.